Background: Bronchiolitis is a lower respiratory tract infection (LRTI) syndrome caused by different viruses. It is the most common LRTI in children under 24 months old, accounting for approximately 90,000 hospitalizations annually and costing over $700 million in children under 12 months. Health care providers vary in diagnosis and management, however. In 2006 the American Academy of Pediatrics (AAP) released guidelines for bronchiolitis management in an effort to standardize clinical practice. Part of these guidelines recommends patients admitted to the hospital receive supplemental oxygen if they are persistently hypoxic, which is defined as pulse oximeter readings persistently below 90%. However, this recommendation is based on expert opinion.